Eurorack module testing tool (DIY)


Anyone in here has a housing/box available for the Eurorack Module tester ?


Contact fcd72 :wink:


has anybody a good tip about where I can find a good 12VAC psu in Europe?


I got my 9VAC adapter for Ambika from - they have 12VAC adapters also.


9VAC Supply buy:
7,99 € 1x AC power supply 9VAC/1000mA
Best-Nr. NV041
7,75€ 1x AC power supply 9VAC/950mA
Best-Nr. 730-0174

I use the same for my DIY Synth “WAVE 1”


12v AC: I got mine from ebay:

12v AC/AC 0.5A

12v AC/AC 1A

12v AC/AC 1.6A

I have all these (using the first one for the module tester), and they work fine !
I like the last one best …


Hi guys, noob here.

Starting to learn some electronics with the
eurorack tester, great device.

I have the pcb and the components,
my only question is the value of the mysterious
R14 resistor (depending on LCD model - 0 ohm to 100 ohm).

My LCD is the Mouser: 763-0216K1Z-NSA-FBW.
(the same from the official BOM)

I dont want to disturb Olivier with this stupid question.

Thanks all.


@PeterSt – all Newhaven 763-0216K1Z-XXX-XXX I’ve seen require 68 ohm resistor.


Newhaven 763-0216K1Z-* work fine without a protection resistor.


If you are scared: You can always start with 68r, solder it a bit above the PCB, so you later can add another resistor in parallel or short it without desoldering. Standard operation PRocedure over here with unknown LCDs . . .



Now I have no excuse to start soldering like no tomorrow.


fail lol


YOu may have scrambled some resistors - TL07xs can latch up to the positive rail if you exceed 8V….


I know their really isn’t any support regarding the eurorack tester Im sorry to ask for help ive been trying to debug whats going wrong here for the past 2 weeks im sorry im bit over my head I guess. I bought the PCB with the already flashed ATMEGA got these blocked results so I replaced the ATMEGA and still no luck…

Any ideas where I should start looking?

Edit: the rotary encoders changes the amount of bricks when its turned, also selecting different push buttons also changed the lcd characters


For starters, you may want to check if device outputs (CV OUT, CLOCK OUT, AUDIO OUT) output what they should. If they do, MCU is working properly, and the LCD, LED and encoder problems are local to those components. If they don’t, chances are something is wrong with MCU clock or fuses, since pretty much everything is malfunctioning.


Thanks for the help kvitekp, I get audio sounding like a harsh square wave out of the clck out and steady click from the gate out and the audio out sounds like a sine wave. Ill have to test the rest on a scope. Thanks for the help Ill guess Ill start by replacing the components local to the MCU.


That sounds about right. Clock is very fast pulses which would change in frequency depending on clock speed and resolution and Gate is basically on/off voltage which would sound like a click.


Looks like you only have problems with your display… Did you check the soldering on the contrast pot?


> I bought the PCB with the already flashed ATMEGA got these blocked results so I replaced the ATMEGA and still no luck…

By what did you replace the Atmega? If you replaced it with a blank one, nothing is going to happen on the display instead a line of blocks.

The very strange display makes me think something is wrong with the LCD itself.


@joshuagoran okay good to know it’s functioning somewhat as it should that’s a relief thanks!

@shiftr I’ll go over the soldering joints around the contrast pot tomorrow night, hopefully it’s something as simple as a bad solder joint but with inspection without magnification the solder joints seem to look fine

@pichenettes sorry I should of clarified I replaced the atmega and flashed the new blank chip with the precompiled .hex file and changed the fuses to the ones provided on the eurorack tester page

I’ll start by ordering a new lcd maybe something went wrong when soldering or when I was handling it

Thanks again everyone for all the help, I’ll let you know if it’s just a wonky lcd